JP2019193116A - In-building transmission system, optical receiver, capsulation device and decapsulation device - Google Patents

Abstract

To achieve more efficient transmission of a multi-channel signal of 4K/8K than in a conventional way, utilizing a coaxial cable in a multiple dwelling house.SOLUTION: The in-building transmission system, transmitting, through an electric signal, a broadcasting signal in a cable television transmitted through an optical signal in a building, includes, in common, an optical receiver which receives an optical signal including an IP packet of a program and capsulizes, after converting the optical signal into an electric signal, an IP packet of view-requested program through an IP address for distribution before output, and a CMTS (Cable Modem Termination System) which transmits the capsulized IP packet through a channel of a RF (Radio Frequency) signal subjected to orthogonal phase amplitude modulation on the basis of the IP address for distribution, thereby enabling each receiver to receive the channel through a CM (Cable Modem), decodes the capsulization after demodulation and return it to an IP packet of an original program.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an in-building transmission system, an optical receiving device, an encapsulating device, and a decapsulating device, and more particularly to an in-building transmission system in a cable television using an IP (Internet Protocol) signal and an optical receiving device constituting the same. The present invention relates to an encapsulation device and a decapsulation device.

  Currently, cable TV provides broadcasting services such as terrestrial / satellite broadcasting retransmission, community channel broadcasting, and multi-channel broadcasting, and various communication services such as Internet connection, telephone, and VOD (Video On Demand).

  When the cable TV station to the subscriber is an HFC (Hybrid Fiber Coaxial) transmission line, the transmission method of the broadcast service is a transmodulation method that re-modulates with 64QAM (Quadrature Amplitude Modulation) or 256QAM, a frequency conversion pass-through method, The pass-through method is used. In the case of a communication service, a DOCSIS 3.0 (Data Over Cable Service Interface Specifications 3.0) standard for transmitting an IP signal as an RF (Radio Frequency) signal is used (Non-Patent Documents 1 and 2). These broadcast and communication signals have a bandwidth of 6 MHz per wave and are frequency-multiplexed in a frequency band of 90-770 MHz. Then, an optical fiber is transmitted by an SCM (Sub Carrier Multiplexing) transmission method in which light is analog-intensity-modulated by the frequency-multiplexed RF signal voltage. . However, the total transmission capacity of this transmission method is about 3-4 Gbps, and it is said that the bandwidth is tight.

  On the other hand, some cable television operators employ an FTTH (Fiber to the Home) system. In this case, since not only the 90-770 MHz band but also the BS-IF (Intermediate Frequency) band can be frequency-multiplexed and transmitted by the SCM transmission method, a transmission capacity of about 4-6 Gbps can be used for the broadcasting service. It is. The communication service is not multiplexed on the SCM, but is transmitted as a signal of a different wavelength by a transmission method such as G-EPON (Gigabit Ethernet Passive Optical Network) as an IP signal modulated with digital light intensity.

  As described above, the cable television using coaxial cables in the distribution system has already been said to be tight in bandwidth, and in the case of FTTH, it is considered that there is still room in the bandwidth of the broadcast service. At the stage where 8K (Super Hi-Vision) service becomes widespread, it is considered that a larger capacity is required even in the case of the FTTH transmission line.

  As a technique for realizing large-capacity transmission by FTTH, digital light intensity modulation is performed using baseband signals as in the communication system, instead of transmitting the light by analog intensity modulation using RF signals used in current cable television. A technique for transmitting data has been studied (Patent Document 1). As a baseband optical transmission technology for communication, 10G-EPON (Non-Patent Document 3) capable of large-capacity transmission of 10 Gbps was standardized in 2009, and corresponding products have been commercialized. Possibility of optical transmission of large-capacity signals at low cost by using 10G-EPON downlink transmission path coding, and time-division multiplexing of video signals and baseband transmission using IP signals for broadcasting systems There is.

  By the way, when a cable TV operator opticalizes a transmission line (optical fiber), in the case of a detached house, it is relatively easy to opticalize up to each subscriber, and a baseband transmission method can be introduced. . However, in-building transmission lines in apartment houses such as condominiums are outside the jurisdiction of cable television operators, and it is difficult to opticalize each subscriber. There are many facilities in the building that have only transmission lines such as coaxial cables or telephone lines, and there is no space for laying new cables, and there are complicated procedures for optical construction. Cost.

  In the case of a conventional SCM transmission method using analog optical intensity modulation, an optical signal is converted into an RF signal by O / E (optical / electrical) conversion at a V-ONU (Video Optical Network Unit) at the front stage of the coaxial cable, Is transmitted as an electrical signal. However, in the case of a baseband transmission system that performs digital light intensity modulation, it is difficult to attenuate the high-frequency component to transmit the O / E converted baseband signal as it is. For this reason, a means for transmitting a large-capacity baseband signal in the transmission line in the building is required.

  As a means for realizing this, IP broadcasting using a transmission / reception device compatible with the DOCSIS 3.0 standard for communication is being studied by cable television operators (Non-Patent Document 4). This is because a CMTS (Cable Modem Termination System) or CMC (Coax Media Converter), which is a transmission device, is installed at a point where the optical fiber is changed to a coaxial cable in the middle of the transmission path, and the IP signal is multicast to the CM (Cable Modem) in the house. Is to be transmitted. By using the channel bonding technique in the DOCSIS 3.0 standard, a large capacity transmission of about 300 Mbps is possible by bonding 256 channels of 256QAM signals. Further, the CM can dynamically change the bonding group received by DBC (Dynamic Bonding Change), and can also receive a channel in another bonding group.

  This DOCSIS 3.0 standard CMTS is installed in the condominium, CM is installed in each receiver (subscriber) 's house, and 4K / 8K signals are transmitted by IP multicast. Systems (distribution methods) are being studied.

  One is a method of dynamically switching transmission programs using channel bonding and IP multicast transmission of the programs. Based on FIG. 9, the 1st in-building transmission system examined conventionally and its delivery system are demonstrated. FIG. 9 shows the process until a program delivered to an apartment house (a condominium, etc.) via an optical fiber is delivered to each receiver's house. The in-building transmission system includes an optical receiver 91, a CMTS 92, and CMs 931 to 942. The optical receiver 91 and the CMs 931 to 942 are connected by a coaxial cable.

  The optical receiving device 91 receives program data (for example, baseband signal) of all programs received via an optical fiber (not shown), converts the program data into an electric signal, and transmits the program requested to be viewed as an IP signal. To the CMTS 92.

The CMTS 92 associates a channel that can be received by the receiver with the requested program data, and further combines the channels to form a bonding group (a group of bonded channels; hereinafter simply referred to as “bonding”). )make. In the figure, one black trapezoid indicates one channel. For example, the black trapezoid is composed of a 256QAM signal having a predetermined carrier frequency and is frequency-multiplexed and transmitted. When the 8K ₁ program is requested via the CM 931 of the group 1, the data of the 8K ₁ program is associated with the bonding 1 channel.

  The CMs 931 to 942 are installed in each receiver's home, receive a predetermined bonding, demodulate and decode the channel signal, and generate a video stream of the program. In this case, since the number of bondings that can be received is limited by the number of CM tuners, a plurality of service groups 93 and 94 composed of a small number of households (recipients' homes) are created, and multicasting is performed within each group. CMs in each service group receive a fixed bonding channel. For example, CM 931 and 932 in group 1 receive bonding (channel) 1 and CMs 941 and 942 in group 2 receive bonding 2. When there is a program viewing request from the CMs 931 to 942 to the CMTS 92, the CMTS 92 dynamically changes the program transmitted by each bonding. If the number of CM tuners is 8 and all 8 channels are 256QAM transmission, the transmission capacity is about 300 Mbps, and this band is shared by households in the service group.

  Another method using the DOCSIS 3.0 standard is a method of performing IP multicast transmission while changing the bonding (channel) received using DBC. Based on FIG. 10, a second in-building transmission system that has been conventionally studied and its distribution method will be described. The in-building transmission system of FIG. 10 includes an optical receiver 91, a CMTS 92, and CMs 95 to 98. The optical receiver 91 and the CMs 95 to 98 are connected by a coaxial cable.

  The optical receiving device 91 receives program data (for example, baseband signal) of all programs received via an optical fiber (not shown), converts the program data into an electric signal, and transmits the program requested to be viewed as an IP signal. To the CMTS 92.

  The CMTS 92 associates the channel with the program data to be transmitted, and further combines the channels to create a bond composed of a plurality of channels. In this case, the correspondence between the program and the channel that transmits the program is set in advance.

The CMs 95 to 98 are installed in each receiver's house, receive a desired bonding (channel), demodulate and decode the channel signal, and generate a video stream of the program. Each CM changes the bonding received in response to a viewing request instead of a fixed bonding. For example, when CM1 (95) views program 1 (8K ₁ ), it receives bonding 1, and when it views program 2 (8K ₂ ), it receives bonding 2. The same applies to other CMs. Therefore, when the same program is viewed at a plurality of subscriber homes, it can be efficiently transmitted by multicast.

Japanese Patent Laying-Open No. 2006-152539

CableLabs DOCSIS 3.0 specifications JCTEA STD-024-1.0 “CATV High-Speed Data Transmission Equipment DOCSIS3.0” IEEE edition, `` IEEE Std 802.3av-2009 '' Ministry of Internal Affairs and Communications Press Material Study Group on Cable Television Video Distribution for the 4K / 8K Era Material 1-4 “Current Status of the Cable Industry and IP Broadcasting” (2017)

  By using CMTS and CM conforming to the DOCSIS 3.0 standard, 4K / 8K signals can be transmitted by IP multicast. However, the following two problems have been encountered in the two in-building transmission systems that have been studied in the past. is there.

In the case of the first in-building transmission system shown in FIG. 9, when receivers (subscribers) of different service groups request viewing of the same program, the same signal is transmitted by a plurality of bondings (for example, The situation where the program 8K ₁ is simultaneously transmitted by the bonding 1 and the bonding 2) occurs, and the band cannot be used effectively. Since the transmission capacity of 8K is about 100 Mbps, for example, if the same 8K program is transmitted by bonding of about 300 Mbps, 1/3 of the band is wasted.

  In the case of the second in-building transmission system shown in FIG. 10, in order to perform DBC in response to a program viewing request (IP multicast join signal) from a CM, it is determined in advance which program (transmission) is transmitted to which bonding (channel). It is necessary to know, and it is necessary to fix each bonding and the IP address of the program to be transmitted and transmit by multicast. That is, a certain bonding needs to be set in advance to transmit a packet of this IP address, and this setting cannot be changed dynamically in the existing DOCSIS standard. In this case, in order for the receiver (subscriber) to be able to select all programs, the CMTS needs a transmission capacity that can always transmit all programs regardless of the number of households. Alternatively, the number of programs that can be viewed is limited by the upper limit of the transmission capacity.

  As described above, the in-building transmission system that has been conventionally studied consumes bandwidth and limits the number of programs, and thus requires a more efficient distribution method. Specifically, there is a need for means for efficiently distributing a program on a coaxial cable whose bandwidth is limited compared to an optical fiber.

  Accordingly, the present invention has been made in view of such a situation, and an object of the present invention is to provide a coaxial cable and a communication transmitter / receiver that are widely used as an in-building transmission line of an apartment house (apartment, etc.). Provided are an in-building transmission system that can be utilized and capable of transmitting a 4K / 8K multi-channel signal more efficiently than before, and an optical receiver, an encapsulating apparatus, and a decapsulating apparatus constituting the same. There is.

  In order to solve the above-mentioned problems, an in-building transmission system according to the present invention is an in-building transmission system for transmitting a broadcast signal on a cable television transmitted by an optical signal by an electric signal in the building, and transmits an IP packet of a program. An optical receiver that receives an optical signal including and converts it into an electrical signal, encapsulates an IP packet of a program requested to be viewed with a distribution IP address, and outputs the encapsulated IP packet for the distribution CMTS (Cable Modem Termination System) that transmits in a channel of an RF (Radio Frequency) signal subjected to quadrature amplitude modulation based on the IP address, and each receiver uses the CM (Cable Modem) to transmit the channel. Is received, demodulated, and then decapsulated and returned to the IP packet of the original program.

  In order to solve the above problems, an in-building transmission system according to the present invention is an in-building transmission system for transmitting a broadcast signal on a cable television transmitted by an optical signal by an electric signal in the building, An optical receiving device that receives an optical signal including a packet, converts it into an electrical signal, and outputs an IP packet of a program requested to be viewed, and encapsulates the IP packet of the program requested to be viewed with a distribution IP address An encapsulation device, and a CMTS (Cable Modem Termination System) that transmits the encapsulated IP packet on a channel of an RF (Radio Frequency) signal subjected to quadrature phase amplitude modulation based on the IP address for distribution. Each receiver receives the channel by CM (Cable Modem), demodulates it, decapsulates it, and unencapsulates the IP channel of the original program. And returning to Tsu door.

  In the intra-building transmission system, the CMTS preferably performs multicast transmission by bonding the channels.

  In the in-building transmission system, it is preferable that the CMTS and the CM correspond to a DOCSIS (Data Over Cable Service Interface Specifications) standard.

  In the intra-building transmission system, the encapsulation is performed based on an encapsulation table in which a correspondence relationship between a program IP address and a distribution IP address is set, and the encapsulation table is updated based on a program viewing request. It is desirable to do.

  In order to solve the above problems, an optical receiver according to the present invention receives an optical signal including an IP packet of a cable television program, and outputs the IP packet of a program requested to be viewed to a CMTS (Cable Modem Termination System). An optical receiving device that converts the optical signal into an electrical signal, a transmission path encoding / decoding unit that decodes the electrical signal and generates an IP packet of the program, A demultiplexing unit that separates and outputs the IP packet of the program requested to be viewed from the IP packet of the program, a capsule in which the correspondence between the IP address for distribution corresponding to the CMTS channel and the program IP address is set An encapsulation unit that encapsulates an IP packet of a program output from the demultiplexing unit with an IP header of the IP address for distribution based on a demultiplexing table; Characterized in that it comprises.

  The optical receiver preferably updates the encapsulation table based on a program viewing request.

  In order to solve the above-described problems, an encapsulation apparatus according to the present invention is an encapsulation apparatus that encapsulates and outputs an IP packet of a cable television program, and is used for distribution corresponding to a CMTS (Cable Modem Termination System) channel. An encapsulation table in which a correspondence relationship between an IP address and a program IP address is set, and a capsule that encapsulates an input program IP packet with an IP header of the distribution IP address based on the encapsulation table And a conversion unit.

  Moreover, it is desirable that the encapsulation device updates the encapsulation table based on a program viewing request.

  In order to solve the above-described problems, a decapsulation device according to the present invention is a decapsulation device that receives an IP packet of an encapsulated cable television program, and a distribution IP address in a CMTS (Cable Modem Termination System) And an encapsulation table in which a correspondence relationship with the program IP address is set, a multicast protocol conversion unit that converts a multicast join signal into a predetermined format that can be supported by the CMTS, and the encapsulation table And a decapsulation unit that decapsulates the IP packet of the encapsulated program.

  Further, it is desirable that the decapsulation device updates the encapsulation table based on a program viewing request.

  The present invention uses an existing coaxial cable and a communication transmitter / receiver to transmit a multi-channel 4K / 8K signal more efficiently than before in an in-house transmission line of an apartment house where only a coaxial cable is laid. Make it possible.

1 is an overall view of an FTTH transmission system including an in-building transmission system of the present invention. It is a figure explaining the ridge transmission system of this invention, and its delivery system. It is a block diagram which shows the structural example of the optical receiver of this invention. It is a block diagram which shows the structural example of the decapsulation apparatus of this invention. It is a setting example of multicast of CMTS used in the present invention. It is an example of a structure of the encapsulation table utilized by this invention. It is an example of a structure of the encapsulation table when address allocation is changed by a viewing request. It is a comparison figure of the calculated value of the number of households of an apartment house, and required transmission capacity. It is a figure explaining the 1st in-building transmission system examined conventionally and its delivery system. It is a figure explaining the 2nd transmission system in a building examined conventionally, and its delivery system.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows an overall view of an FTTH transmission system in a cable television including the in-building transmission system of the present invention. In the following, a case where a baseband transmission method is introduced into the FTTH transmission line will be described as an example. However, the present invention is not limited to the baseband transmission method, and a method capable of transmitting program data (IP signals) of all programs using an optical transmission line. If so, the signal may be transmitted by any transmission method on the FTTH transmission path.

  The FTTH transmission system shown in FIG. 1 includes one cable television station 1, an arbitrary number of detached houses 2 and apartment houses 3, and an optical transmission path 4 made of an optical fiber connecting them. The cable television station 1 includes an optical transmission device 5, converts a video signal into an optical signal, and outputs the optical signal to the optical transmission line 4 by, for example, baseband transmission. The optical signal is branched (amplified and distributed) and transmitted to the receiver (subscriber) house or the housing complex where the receiver is located.

  The detached house 2 includes an optical receiver 10, an IP-STB (Set Top Box) 50, and a TV (television) 60.

  The optical receiver 10 receives program signals (for example, baseband signals) of all programs that have arrived via the optical transmission line 4, and performs O / E (optical / electrical) conversion, decoding, channel selection, and the like. Only the video stream to be viewed (IP packet of the program) is output to the IP-STB 50. As will be described later, the optical receiver 10 can be shared with the optical receiver 10 used in the apartment house 3.

  The IP-STB 50 requests the optical receiver 10 for a program desired to be viewed, receives a video stream (program IP packet) from the optical receiver 10, converts it into a signal that can be viewed on a general television, Output to TV60.

  The receiver (viewer) can view a desired program on the TV 60.

The apartment house (condominium, etc.) 3 is provided with an in-building transmission system for transmitting broadcast signals on cable television transmitted with optical signals using electrical signals within the building. The collective housing 3 includes an optical receiver 10 and a CMTS 20 that are used jointly (commonly), a CM 30 (30 ₁ to 30 _n ) and a decapsulator 40 (40 ₁ to 40 _n ) installed in each receiver's house. , IP-STB 50 (50 ₁ to 50 _n ), and TV 60 (60 _{1 to} 60 _n ).

  Hereinafter, based on FIG. 2, the building transmission system of the present invention and the distribution method thereof will be described.

  The optical receiver 10 receives program signals (for example, baseband signals) of all programs that have arrived via the optical transmission path 4, and performs O / E (optical / electrical) conversion, decoding, channel selection, and the like. As will be described later, the optical receiving device 10 includes an IP encapsulation processing unit 12 and adds a distribution IP address (in this example, an IPv4 address) to a video stream (program IP packet) requested to be viewed. Then, IP encapsulation is performed, and the encapsulated signal is output to the CMTS 20. In the case of an apartment house, the optical receiver 10 and the CMTS 20 can be installed in a common space such as an MDF (Main Distributing Frame) room in the apartment.

  The CMTS 20 associates the program data input from the optical receiver 10 with the bonding (channel) based on the distribution IP address. That is, it is set in advance which channel or bonding is used to transmit the signal of each distribution IP address, and the program data input from the optical receiver 10 is distributed to the viewing household (CM 30 of each receiver's house) by multicast. To do. In the figure, one black trapezoid represents one channel, which is composed of, for example, a 256QAM signal having a predetermined carrier frequency and transmitted as a frequency-multiplexed RF signal. Each channel or bonding is associated with program data encapsulated with a distribution IP address. The CMTS 20 outputs a multicast join signal, which is a viewing request from the receiver, to the optical receiving device 10, and the optical receiving device 10 controls the encapsulated IP address (distribution IP address), thereby viewing the program being viewed. Only transmit. This CMTS 20 can use an off-the-shelf DOCSIS 3.0-compliant transmission device.

  FIG. 5 shows an example of CMTS multicast setting (ie, correspondence between bonding and IP address for distribution). In this example, the CMTS 20 has a channel capacity of 300 Mbps by bonding 8 channels (frequency 93 to 135 MHz) of 256QAM channels as bonding 1. Using this bonding 1, it is set so that a program with a distribution IP address (multicast IPv4 address) from 225.0.01 to 225.0.0.6 is transmitted by multicast.

  Here, in order to perform large-capacity transmission, channel bonding is premised. However, if the correspondence relationship between the IP address for distribution and the channel is set, program data (encapsulated IP packet) can be used alone. May be transmitted on the other channel (QAM signal). The transmission method is not limited to multicast, and unicast transmission may be used.

CM1 to CMn (30 ₁ to 30 _n ) are installed in each receiver's house, receive a bond (channel) through which a program for which viewing is requested is transmitted, demodulate and decode the channel signal, and program video stream ( Here, an IP packet of the encapsulated program is generated. For example, when CM1 (30 ₁ ) views program 8K ₁ , bonding 1 is received, and when CM2 (30 ₂ ) views program 8K ₂ , bonding 2 is received. The IP packet of the encapsulated program obtained by demodulation and decoding is output to the decapsulation device 40. For these CM1 to CMn (30 ₁ to 30 _n ), an off-the-shelf DOCSIS3.0-compliant receiving device can be used.

  The CMTS and CM may be compliant with the DOCSIS 3.1 standard in addition to those compliant with the DOCSIS 3.0 standard.

The decapsulation device 40 (40 ₁ to 40 _n ) decapsulates the IP packet of the encapsulated program input from the CM 30. That is, the distribution IP address (IP header) is deleted from the encapsulated IP packet, and the original program data (program IP packet) is returned to the IP-STB 50. Details will be described later. The functions and operations of the subsequent IP-STB 50 (50 ₁ to 50 _n ) and TV 60 (60 _{1 to} 60 _n ) are the same as those of the detached house.

  FIG. 3 is a block diagram showing a configuration example of the optical receiver 10 of the present invention.

  The optical receiver 10 includes a transmission path decoding / demultiplexing unit 11 and an encapsulation processing unit 12. Furthermore, in order to allow the optical receiver 10 to be shared between the detached house and the apartment house, the flow of the video stream is different between the transmission in the detached house and the intra-building transmission in the apartment house. Distribution route control units 13 and 14 to be controlled can be provided. When the optical receiver 10 is dedicated to the in-building transmission system, the distribution route at the time of detached transmission is unnecessary, and the distribution route control units 13 and 14 may be omitted. The transmission path decoding / demultiplexing unit 11 includes an O / E conversion unit 111, a transmission path encoding / decoding unit 112, and a multiplexing / demultiplexing unit 113, and the encapsulation processing unit 12 includes a capsule Table 100 and IPv4 / IPv6 encapsulation unit 121. Hereinafter, the function of each block will be described.

  The O / E (optical / electrical) conversion unit 111 converts an optical signal transmitted from the optical transmission device 5 (for example, program data transmitted through baseband) into an electric signal, and sends it to the transmission path coding / decoding unit 112. Output.

  The transmission path encoding / decoding unit 112 decodes the transmission path encoding performed on the transmission side for the transmission data that has become an electric signal. This processing includes, for example, performing deinterleaving processing on the interleaving performed on the transmission side, performing error correction processing, and the like. All the decoded program data (program IP packet) is output to the demultiplexing unit 113.

  The demultiplexing unit 113 separates and outputs the video stream selected based on the program viewing request from the IP-STB of the receiver (subscriber) with respect to the decoded video stream of all program data. Here, during detached transmission, the distribution route control units 13 and 14 output the signal (IPv6 video stream) output from the demultiplexing unit 113 as it is as the output of the optical receiver 10. On the other hand, at the time of intra-building transmission, the selected and separated video stream is output to the encapsulation processing unit 12.

  In the IPv4 / IPv6 encapsulation unit 121, the encapsulation processing unit 12 encapsulates the separated video stream (program IP data) and outputs the result. Specifically, an IP packet of a program (video signal) requested to be viewed is IP-encapsulated with an IP header of a distribution IP address set so as to be transmitted by a CMTS in the subsequent stage and output. The distribution IP address to be encapsulated is determined with reference to the encapsulation table 100. When an unviewed program or a newly viewed program is requested, the encapsulation table 100 is updated to control the program to be distributed.

  FIG. 6 shows a configuration example of the encapsulation table 100. Since program 1 (8K) to program 6 (4K) are being viewed, the original IP addresses of these programs (sometimes referred to as program IP addresses, in this example, IPv6 addresses) are IP addresses for distribution (this In the example, encapsulation is performed with IPv4 address). The distribution IP address corresponds to a channel or bonding transmitted by CMTS. If the receiver stops watching program 6 and starts watching program 8 (4K), the encapsulation table is updated as shown in FIG. 7 (distribution IP address 225.0.0.6 is the original IP address of program 8). By updating to correspond to FF02 :: 08), it is possible to change the program to be transmitted without changing the setting of the CMTS.

  In the examples of FIGS. 2 and 3, the encapsulation is performed using the IPv4 header because it is assumed that the subsequent CMTS supports only IPv4. In this case, the IPv4 header is used. Encapsulate. If the subsequent CMTS supports IPv6 multicast, it is encapsulated with an IPv6 header. If only unicast can be transmitted, it is encapsulated in IPv4 / IPv6 unicast. All the transmission of the IP packet of the program follows the setting of the CMTS and the setting of the encapsulation table.

  Further, the optical receiving device 10 may be used integrally with the CMTS 20. In addition, the optical receiver has been described as a baseband optical receiver (data down-dedicated device) so far, but this is replaced with another IP signal receiver, for example, a 10G-EPON receiver (data downstream and upstream compatible device). The encapsulation processing unit 12 may be installed in the 10G-EPON receiving apparatus and connected to the CMTS of the in-building transmission system.

  3 may be configured to be separated into an optical receiving device including a transmission path decoding / demultiplexing unit 11 and an encapsulation device including an encapsulation processing unit 12 (not shown). ). At this time, the optical receiving apparatus receives the optical signal including the IP packet of the program, converts it into an electrical signal, and outputs the IP packet (IPv6 video stream in FIG. 3) requested to be viewed to the encapsulating apparatus. The encapsulating apparatus encapsulates the IP packet of the program requested to be viewed with the distribution IP address based on the encapsulation table, and outputs the encapsulated IP packet to the CMTS at the subsequent stage.

  FIG. 4 is a block diagram showing a configuration example of the decapsulation device 40 of the present invention.

  The decapsulation device 40 includes a multicast protocol conversion unit 41, an IPv4 / IPv6 decapsulation unit 42, and an encapsulation table 100. The encapsulation table 100 is the same as the encapsulation table 100 of the optical receiver 10 and is updated in synchronization with the optical receiver 10.

The operation of the multicast protocol conversion unit 41 and the procedure for synchronous update of the encapsulation table 100 are as follows. When a multicast join signal that is a program viewing request is received from the IP-STB 50, the multicast protocol conversion unit 41 transmits information indicating that there is a program viewing request and the IP address of the viewing request program to the optical receiving device 10 by unicast. Based on the information from the decapsulation device 40, the optical reception device 10 updates its own encapsulation table 100 so as to transmit with a bonding QAM signal having a free band. Then, the update information of the encapsulation table is transmitted to each decapsulation device 40 (40 ₁ to 40 _n ), and the encapsulation tables 100 of all the decapsulation devices 40 are updated. Based on the updated encapsulation table 100, the decapsulation device (multicast protocol conversion unit 41) transmits to the optical reception device 10 a program viewing request (multicast join signal) in which the original IP address of the program is changed to the distribution IP address. To do. At this time, when the CMTS is compatible with IPv4, it is converted into IGMP (Internet Group Management Protocol), and when it is compatible with IPv6, it is converted into MLD (Multicast Listener Discovery). At this time, IGMPv2 or MLDv1 that does not need to specify a source address is used.

  Then, the IPv4 / IPv6 decapsulation unit 42 identifies the IPv6 / IPv4 encapsulated video packet input from the CM with reference to the encapsulation table 100, and unencapsulates the original video signal (original IP address). The IP packet of the program that is held is returned to the IP-STB 50 and the TV 60. The decapsulation device 40 may be incorporated in the CM 30 or the IP-STB 50 as a decapsulation unit. In this example, the data encapsulated by the IPv4 header is input. However, when the CMTS 20 is IPv6-compatible, the data encapsulated by the IPv6 header is input, and the IPv6 header is deleted and the original data is deleted. Return to the program data.

  A transmission procedure in the building transmission system of the present invention will be briefly described with reference to FIG.

(1) In the CMTS 20, the correspondence between the distribution IP address and the transmission channel or bonding is preset.

(2) A viewing request for a program (for example, program 1: 8K ₁ ) from the IP-STB at the receiver's house is transmitted to the optical receiver 10 via the decapsulator 1 (40 ₁ ).

(3) The correspondence between the distribution IP address and the original IP address (program IP address) of the requested program is set in the encapsulation table. For example, the original IP address of program 1 is set to correspond to the distribution IP address of bonding 1. This setting is reflected in all of the encapsulation tables of the IP encapsulation processing unit 12 and the decapsulation devices ₁ to _n (40 ₁ to 40 _n ).

(4) The optical receiver 10 encapsulates the requested program 1 IP packet with the IP header of the bonding IP address for delivery according to the setting of the encapsulation table and outputs the result.

(5) The CMTS 20 transmits the IP packet of the encapsulated program 1 through the bonding 1, and instructs the CM 1 (30 ₁ ) to receive the bonding 1.

(6) CM1 (30 ₁ ) receives program 1 (8K ₁ ) through bonding 1.

(7) The decapsulation device 1 (40 ₁ ) restores the encapsulated packet and outputs the video data (8K ₁ ) of program 1.

  In this way, all programs can be transmitted using a small number of channels by using encapsulation.

(Verification of effect)
In order to confirm the effect of the in-building transmission system described above, verification is performed using specific numerical values.

  First, as the condition setting, 30 households are assumed as the number of condominiums, 2K (10 Mbps) is 100 programs, 4K (40 Mbps) is 18 programs, and 8K (100 Mbps) is 1 program with a total transmission capacity of 1 Assume .8 Gbps. Each household can view up to two programs simultaneously. The CMTS to be used transmits 256 QAM signals (38 Mbps) with a maximum of 8 channel bonding, and outputs 32 channel QAM signals per card. The transmission capacity per bonding group is about 300 Mbps at 38 Mbps × 8 ch. The transmission capacity per card is 38 Mbps × 32 = 1216 Mbps. The CM receives signals bonded by eight multi-tuners. When DBC is performed, video is transmitted on the secondary channel 7ch other than the primary channel 1ch, and the secondary channel is switched on the DBC.

  The case where the first conventional transmission system (FIG. 9) is used will be verified. When transmitting 8K for one program and 4K for 5 programs, a transmission capacity of 300 Mbps is required. Considering viewing 6 programs simultaneously in 3 households, 3 households are accommodated per bonding group (300 Mbps). Since multicasting is not possible between different service groups, 10 bonding groups are required for 30 households. Therefore, an 80ch 256QAM signal (3 Gbps) is required.

  The case where the second conventional transmission system (FIG. 10) is used will be verified. In order to be able to select all programs in each household, all programs must be transmitted. Dividing all programs (1.8 Gbps) by 38 Mbps / channel gives 48 channels. If 2ch is a primary channel and the remaining 48ch is a secondary channel, a 50ch 256QAM signal (about 1.9 Gbps) is required. However, it is an approximate value, and is calculated on the assumption that the total transmission capacity of a plurality of programs is accurately contained in the bonding group.

  The case where the in-building transmission system of the present invention (FIG. 2) is used will be verified. In this case, since multicast transmission is possible, the maximum transmission capacity for simultaneous viewing may be designed. There are 30 households, and considering simultaneous viewing up to 2 programs in each household (60 programs in total), 8K1 program (100 Mbps) + 4K18 program (40 Mbps × 18) + 2K41 program (10 Mbps × 41) = 1230 Mbps. Dividing the maximum transmission capacity (1230 Mbps) for simultaneous viewing by 38 Mbps / channel gives 33 channels. If 2ch is a primary channel and the remaining 33ch is a secondary channel, a 35ch 256QAM signal (about 1.3 Gbps) is required.

  Thus, it can be seen that the in-building transmission system of the present invention can transmit with a smaller transmission capacity than the conventional transmission system. In this example, each household can select up to two programs at the same time. Further, in the case of the present invention, when each household views the same program, it can be efficiently transmitted by multicast, and the free bandwidth can be effectively used for data communication or the like.

  FIG. 8 shows a comparison of the calculated values of the number of households in an apartment house and the required transmission capacity. The horizontal axis is the number of recipients' households, and the vertical axis is the transmission capacity required for the transmission line in the building.

  Since the first conventional transmission system (conventional system 1) requires a transmission capacity of 300 Mbps for every three households, it can be seen that the necessary transmission capacity increases linearly according to the number of households. It can also be seen that the second conventional transmission system (conventional system 2) always requires a transmission capacity for all programs regardless of the number of households. In the case of the present invention, since the transmission capacity of the number of households × the bandwidth of the viewing program × 2 is required, the necessary transmission capacity gradually increases according to the number of households. Since a band for transmitting all programs is required in about 50 households, the graph is the same as that of the conventional system 2 in the case of 50 households or more. Therefore, in this example of the number of programs, when there are 50 households or less, the in-building transmission system of the present invention can efficiently transmit programs to each household with a smaller transmission capacity than the conventional system, and select all programs. It can be seen that.

  As described above, when the baseband transmission method is introduced into the FTTH system of the cable television, the present invention addresses the problem of establishing an efficient transmission means for 4K / 8K multi-channel signals in an in-building transmission line such as an apartment. Is a method that can solve this problem.

  In the above embodiment, the configuration of the in-building transmission system has been described. However, the present invention is not limited to this, and is configured as a transmission method for transmitting program data using a coaxial cable in an apartment house. Also good. That is, according to the data flow of FIG. 2, it may be configured as a transmission method for transmitting program data (program IP packets) to a plurality of recipients using IP multicast transmission.

  Although the above embodiment has been described as a representative example, it will be apparent to those skilled in the art that many changes and substitutions can be made within the spirit and scope of the invention. Therefore, the present invention should not be construed as being limited by the above-described embodiments, and various modifications and changes can be made without departing from the scope of the claims. For example, a plurality of constituent blocks described in the embodiments can be combined into one, or one constituent block can be divided.

DESCRIPTION OF SYMBOLS 1 Cable television station 2 Detached house 3 Apartment house 4 Optical transmission line 5 Optical transmitter 10 Optical receiver 11 Transmission path decoding and demultiplexing part 12 Encapsulation processing part 13 and 14 Distribution route control part 20 CMTS
30 CM
40 Decapsulator 41 Multicast protocol converter 42 IPv4 / IPv6 decapsulator 50 IP-STB
60 TV
91 Optical receiver 92 CMTS
93,94 Service Group 95-98 CM
100 Encapsulation Table 111 O / E Conversion Unit 112 Channel Encoding / Decoding Unit 113 Demultiplexing Unit 121 IPv4 / IPv6 Encapsulation Unit

Claims (11)

An in-building transmission system for transmitting a broadcast signal on a cable television transmitted with an optical signal with an electric signal in the building,
An optical receiver that receives an optical signal including an IP packet of a program, converts the signal into an electric signal, encapsulates and outputs the IP packet of the requested program for viewing with an IP address for distribution;
CMTS (Cable Modem Termination System) that transmits the encapsulated IP packet on a channel of RF (Radio Frequency) signal subjected to quadrature amplitude modulation based on the IP address for distribution;
In common,
An in-building transmission system characterized in that each receiver receives the channel by CM (Cable Modem), demodulates it, and then decapsulates it to return it to the IP packet of the original program. An in-building transmission system for transmitting a broadcast signal on a cable television transmitted with an optical signal with an electric signal in the building,
An optical receiver that receives an optical signal including an IP packet of a program, converts the optical signal into an electrical signal, and outputs an IP packet of the program requested to be viewed;
An encapsulation device for encapsulating the IP packet of the program requested to be viewed with a distribution IP address;
CMTS (Cable Modem Termination System) that transmits the encapsulated IP packet on a channel of RF (Radio Frequency) signal subjected to quadrature amplitude modulation based on the IP address for distribution;
In common,
An in-building transmission system characterized in that each receiver receives the channel by CM (Cable Modem), demodulates it, and then decapsulates it to return it to the IP packet of the original program. In the building transmission system according to claim 1 or 2,
The CMTS is an intra-building transmission system in which the channels are bonded and multicast transmission is performed. In the ridge transmission system according to any one of claims 1 to 3,
The in-building transmission system, wherein the CMTS and the CM correspond to a DOCSIS (Data Over Cable Service Interface Specifications) standard. In the ridge transmission system according to any one of claims 1 to 4,
The encapsulation is performed based on an encapsulation table in which a correspondence relationship between a program IP address and a distribution IP address is set, and the encapsulation table is updated based on a program viewing request. Transmission system. An optical receiver that receives an optical signal including an IP packet of a cable television program and outputs an IP packet of a program requested to be viewed to a CMTS (Cable Modem Termination System),
An O / E converter that converts the optical signal into an electrical signal;
A transmission path encoding / decoding unit that decodes the electrical signal to generate an IP packet of the program;
A demultiplexing unit that separates and outputs the IP packet of the program requested to be viewed from the IP packet of the decoded program;
Based on the encapsulation table in which the correspondence relationship between the distribution IP address corresponding to the channel of the CMTS and the program IP address is set, the IP packet of the program output from the demultiplexing unit is converted to the distribution IP. An encapsulation unit that encapsulates the IP header of the address;
An optical receiver comprising: The optical receiver according to claim 6,
An optical receiving apparatus, wherein the encapsulation table is updated based on a program viewing request. An encapsulation device that encapsulates and outputs IP packets of a cable television program,
An encapsulation table in which a correspondence relationship between a distribution IP address corresponding to a CMTS (Cable Modem Termination System) channel and a program IP address is set;
An encapsulation unit that encapsulates an IP packet of an input program with an IP header of the IP address for distribution based on the encapsulation table;
An encapsulation device comprising: The encapsulation device according to claim 8,
An encapsulation apparatus, wherein the encapsulation table is updated based on a program viewing request. A decapsulating device for receiving an IP packet of an encapsulated cable television program,
An encapsulation table in which the correspondence between a distribution IP address in CMTS (Cable Modem Termination System) and a program IP address is set;
A multicast protocol conversion unit that converts a multicast join signal into a predetermined format that can be supported by the CMTS, and
A decapsulation unit that decapsulates an IP packet of the encapsulated program with reference to the encapsulation table;
A decapsulation device. The decapsulation device according to claim 10,
The decapsulation apparatus updates the encapsulation table based on a program viewing request.

Images